To create EXE type files, bcompiler has to be used with a modified sapi
file or a version of PHP which has been compiled as a shared library. In
this scenario, bcompiler reads the compressed bytecode from the end of the
exe file.

bcompiler can improve performance by about 30% when used with uncompressed
bytecodes only. But keep in mind that uncompressed bytecode can be up
to 5 times larger than the original source code. Using bytecode
compression can save your space, but decompression requires much more
time than parsing a source. bcompiler also does not do any bytecode
optimization, this could be added in the future...

In terms of code protection, it is safe to say that it would be impossible
to recreate the exact source code that it was built from, and without the
accompanying source code comments. It would effectively be useless to use
the bcompiler bytecodes to recreate and modify a class. However it is
possible to retrieve data from a bcompiled bytecode file - so don't put
your private passwords or anything in it.